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Amp Fluttering

Discussion in 'Amp Central Station' started by bayside, Jan 8, 2021.

  1. bayside

    bayside Tele-Meister

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    My Mesa Lonestar has a fluttering sound. It seems there's a 60cycles thing about the sound. Also Drive channel has a horrible screech. Tube thing? Others?
     
  2. tubejockey

    tubejockey Tele-Holic

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    The screech is likely a microphonic preamp tube. The "fluttering" may need further questioning. Is it a very low frequency like 10Hz or so, or a low hum like 60Hz? A low hum that cannot be turned down with the master volume is likely a shorted power tube. Look for a red-plating power tube.
     
  3. Wrighty

    Wrighty Friend of Leo's

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    This will be of no help and probably irrelevant but I had an Express for less than a year before the fluttering and screeching saw me out it. The shop I bought it from couldn’t stop it happening.

    Like I say, sorry it’s no help but I feel better to at last have the chance to get it off my chest!
     
  4. tubejockey

    tubejockey Tele-Holic

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    The "fluttering" that you mentioned could be what techs call "motorboating", usually solved with better lead layout and/or grid stopper resistors.
     
  5. Engine Swap

    Engine Swap Tele-Afflicted

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    Age of amp?
     
  6. Wally

    Wally Telefied Ad Free Member

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    Motor boating and 60 cycle hum can be indicators of a filter cap proble. Tech time.
     
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  7. bayside

    bayside Tele-Meister

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    Motor boating is a good description. The Amp is about 10 years old. Living in central Idaho there aren't any techs. Um, maybe I'll try tube rotation. Thanks for all the input!
     
  8. Wally

    Wally Telefied Ad Free Member

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    Fwiw, a filter cap can file at any time. I have replaced a failed filter cap in a 9 year le Fender amp.
    Pull all tubes and fire the amp up...what happens? if the hum and motor boating persist, you probably have a filter cap problem. If the noise is gone, install the power tubes and see what happens. If and when the noise returns, you have found an area of concern.

    Ahhh...central Idaho. Noticing your user name and location, I have to ask....has Cali, Oregon and Washington state slipped into the Pacific and the water is lapping at Idaho’s western prop porch??? Eeeehaw. Perhaps you just have wistful memories of the Bay Area?
    Your amp may need to sent back to Mesa if you don’t find a simple problem causing the noise.
     
  9. bayside

    bayside Tele-Meister

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    Thanks Wally, I'll try that. Ah Mexico is also on the eastern pacific, which is where I'd be if not for the pandemic.
     
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  10. Wally

    Wally Telefied Ad Free Member

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    I agree...so is Peru..and Ecuador...and Panama..Chile. When I read ‘bayside’, the San Francisco Bay comes to mind. No matter...Idaho is a long way from any bay.
    At any rate, good luck with the amp. There are a number of possible reasons for the problems it has.
     
  11. Follylover

    Follylover NEW MEMBER!

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    I am interested in what happened. I agree absolutely with what has been said, but who am I really, just a new guy with no picture. Soon to fix that. Anyway, Greetings! Gerry
     
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